Long QT syndrome (LQTS) affects one in 3,000 live births and is responsible for approximately 4,000 deaths in the United States per year. The syndrome is defined clinically as an increased interval between the onset of the Q wave and the end of the T wave on the electrocardiogram, which represents a prolongation of the myocardial repolarization time. LQTS can either be congenital or acquired as a result of medication or metabolic disturbance. Many congenital forms of LQTS have been described, but the majority of cases are the result of mutations in one of three cardiac ion channel genes: KCNQ1, KCNH2, or SCN5a. Mutations in KCNQ1 or SCN5a lead to LQTS 1 and 3, while defects in KCNH2 (also known as the human ether-a-go-go related gene hERG) lead to LQTS 2.